1. Field of the Invention
This invention relates to a knock control system and method for use in an internal combustion engine equipped with a turbosupercharger and, more particularly, to such a knock control system for controlling the degree of supercharge applied to the engine in accordance with detected knock intensity.
2. Description of the Prior Art
In order to improve internal combustion engine efficiency and performance, a turbosupercharger has been employed to artifically increase the amount of air supplied to the cylinders. With the air pressure rising, however, the air temperature increases in the cylinders, increasing the tendency to knock. Continuous heavy knock may be a cause of abnormal vibrations and local overheat subjecting the engine to abnormal wear and failure. This results in a degradation of engine efficiency and performance.
In order to eliminate the above disadvantages, it is conventional practice to suppress knock by lowering the engine compression ratio. However, this leads to limited engine output and fuel economy and high engine output can be achieved where knock is allowed to some extent.